JPH10273634A - Acrylic tacky agent and acrylic tacky tape or sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject tacky agent excellent in tacky characteristics from ordinary temperature to high temperature and having high peel force at a low speed to a polyolefin which is an adherend having low polarity by including a tackiness-providing resin and a specific reaction product. SOLUTION: This acrylic tacky agent consists essentially of an acrylic copolymer and contains (A) a tackiness-providing resin having a functional group (preferably an esterified product of a rosin-based compound) and (B) a reaction product obtained by reacting a compound capable of reacting with the above functional group (preferably a crosslinking agent) with a part of the component A. Furthermore, an esterified product between a rosin-based compound such as a rosin monomer and a polyhydric alcohol such as diethylene glycol is used as the component A and, in the component B, tolylene diisocyanate, etc., is preferably used as a compound capable of reacting with isocyanate group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic pressure-sensitive adhesive and an acrylic pressure-sensitive adhesive tape or sheet, and has excellent adhesive properties from room temperature to high temperature, and particularly excellent peeling resistance at a low speed to a low-polarity adherend. And an acrylic pressure-sensitive adhesive and an acrylic pressure-sensitive adhesive tape or sheet.

[0002]

2. Description of the Related Art Acrylic copolymer itself has tackiness and can be a pressure-sensitive adhesive without adding a tackifying resin. However, the surface of an adherend having low polarity such as polyethylene or polypropylene can be used. Has a low peeling force. For this reason, as in the case of other pressure-sensitive adhesives, an attempt has been made to improve the peeling force of a low-polarity adherend by adding a tackifier resin (for example, JP-A-3-281587).

However, even if a tackifier resin is added, no significant improvement in the peeling force at a speed lower than the peeling speed based on the peeling test specified in JIS is not observed. In other words, when a constant load is applied for a long time, it is easily peeled off. Also, as in the conventional case, in the case of a mixed system of an acrylic copolymer and a tackifying resin, the mixing of the tackifying resin due to the compatibility of the tackifying resin, the glass transition temperature of the pressure-sensitive adhesive itself and the balance of various tackiness properties, etc. The amount was limited, and even if it was found that the tackifier resin had a large adhesive effect on a low-polarity adherend, the effect could not be sufficiently exerted.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has excellent adhesive properties from room temperature to high temperature, and has a low speed with respect to polyolefin as a low-polarity adherend. It is an object of the present invention to provide an acrylic pressure-sensitive adhesive and an acrylic pressure-sensitive adhesive tape or sheet having a high peeling force.

[0005]

The acrylic pressure-sensitive adhesive according to claim 1 is a pressure-sensitive adhesive containing an acrylic copolymer as a main component, and the pressure-sensitive adhesive has a functional group-containing tackifier. It is characterized by containing a reaction product of a resin, a compound capable of reacting with the functional group, and a part of the tackifier resin.

The acrylic pressure-sensitive adhesive tape or sheet according to claim 4 is a pressure-sensitive adhesive tape or sheet in which a pressure-sensitive adhesive layer containing an acrylic copolymer as a main component is provided on one surface of a substrate. On the layer surface, a tackifier resin having a functional group, and a surface layer in which a cross-linking agent capable of reacting with the functional group and a part of the tackifier resin are formed are formed. .

The acrylic copolymer can be obtained by copolymerizing an alkyl (meth) acrylate alone or another monomer copolymerizable therewith or a vinyl monomer having a hydroxyl group or a carboxyl group. The alkyl (meth) acrylate has 2 to 2 carbon atoms.
Fourteen are preferred. If the carbon number of the alkyl group is out of this range, the properties as a pressure-sensitive adhesive are undesirably deteriorated. The alkyl group preferably has 4 to 9 carbon atoms.

[0008] Such materials include ethyl acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, and t-butyl (meth) acrylate. , N-octyl (meth) acrylate, isooctyl acrylate, 2-ethylhexyl (meth) acrylate, isononyl acrylate, lauryl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

Other monomers copolymerizable with the above alkyl (meth) acrylate are not particularly restricted but include, for example, (meth) acrylonitrile, n-vinylpyrrolidone, n-vinylcaprolactam, acryloylmorpholine, (meth) acrylamide, dimethylamino Vinyl monomers having a highly polar group such as ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and dimethylaminopropylacrylamide; and copolymerizable vinyl monomers such as methyl (meth) acrylate, styrene, and vinyl acetate. The compounding amount of the other copolymerizable monomer is usually 0.5 to 30% by weight.

Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
4-hydroxy (meth) butyl acrylate, caprolactone-modified (meth) acrylate, polyoxyethylene oxide-modified (meth) acrylate, and the like. Examples of the vinyl monomer having a carboxyl group include (meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, fumaric acid, fumaric anhydride and the like.

The amount of the vinyl monomer having a hydroxyl group is preferably 0.05 to 1% by weight. 0.05% by weight
If the amount is less than the above, the degree of crosslinking of the pressure-sensitive adhesive does not increase, and sufficient creep characteristics cannot be obtained. If the amount exceeds 1% by weight, the initial adhesive strength decreases, which is not preferable. More preferably 0.0
7 to 0.8% by weight. The amount of the vinyl monomer containing a carboxyl group is preferably 0.1 to 10% by weight. If the amount is less than 0.1% by weight, the degree of crosslinking of the pressure-sensitive adhesive does not increase and sufficient creep characteristics cannot be obtained. If the amount exceeds 10% by weight, the initial adhesive strength decreases, which is not preferable.
More preferably, it is 0.3 to 7% by weight.

The weight average molecular weight of the acrylic copolymer is preferably 200,000 to 1.5 million. If it is less than 200,000, the necessary cohesive strength cannot be obtained, and if it exceeds 1.5 million, the viscosity becomes high, and the productivity in the mixing and coating process of the tackifying resin is unfavorably deteriorated. A more preferred weight average molecular weight is 300,000 to 1.2 million.

[0013] A chain transfer agent may be added to adjust the weight average molecular weight. As the chain transfer agent, those having high chain transfer properties such as thiol compounds and halogen compounds are suitable. Examples of the thiol compound include n-dodecyl mercaptan, 2-mercaptoethanol, β-mercaptopropionic acid, octyl β-mercaptopropionate, methoxybutyl β-mercaptopropionate, and trimethylolpropane tris (β-thiopropionate). , Butyl thioglycolate, propanethiols,
Butanethiols, thiophosphites and the like. Examples of the halogen compound include, for example, carbon tetrachloride.

The method for producing the acrylic copolymer is not particularly limited, and examples thereof include bulk polymerization, solution polymerization, dispersion polymerization,
Known polymerization methods such as emulsion polymerization can be employed. The method of initiating polymerization in the above polymerization method is also not particularly limited, for example,
A method using a thermal polymerization initiator such as benzoyl peroxide, lauroyl peroxide, or azoisobutyronitrile, or a photopolymerization initiator such as benzoin, benzoin methyl ether, or benzophenone can be used in combination with ultraviolet irradiation, electron gland irradiation, or the like.

The tackifying resin having a functional group includes a tackifying resin having a reactive functional group such as a hydroxyl group, a carboxyl group, a vinyl group, an epoxy group, an isocyanate group, a mercapto group, an amino group, an ester group, A tackifying resin having no group but having the above functional group given by a chemical reaction.

Examples of the tackifying resin having a hydroxyl group, a carboxyl group, or a vinyl group include rosin resins such as esterified rosin compounds and polymerized rosins;
Examples of the tackifier resin having a hydroxyl group and a vinyl group include terpene phenol resins, aromatic modified terpene resins, terpene resins such as rosin phenol resins, and alkylphenol resins.

The above-mentioned esterified rosin compound is an esterified product of a rosin compound and a polyhydric alcohol. The rosin compound is a rosin monomer, a disproportionated rosin, a polymerized rosin, a hydrogenated rosin, Disproportionated rosin and mixtures thereof. Examples of the polyhydric alcohol include diethylene glycol, glycerin, pentaerythritol and the like.

The tackifying resin having an epoxy group includes a tackifying resin having a hydroxyl group, a carboxyl group, and a vinyl group in one molecule such as a diepoxy compound such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate. It is obtained by reacting a compound having two or more epoxy groups.

The tackifying resin having an isocyanate group includes a tackifying resin having a hydroxyl group and a carboxyl group,
Aliphatic or aromatic or alicyclic diisocyanate compound,
It is obtained by reacting a triisocyanate compound.

The tackifier resin having a mercapto group can be obtained by reacting a polymercaptan compound such as a dithiol compound with a tackifier resin having a vinyl group.

The tackifier resin having an amino group is obtained by reacting a polyamine compound such as a diamine compound with the tackifier resin having an isocyanate group.

Examples of the polyvalent amine compound include 4,4 ′
-Methylene-bis- (2-chloroaniline), hydroxypropylated ethylenediamine, N, N-dimethylcyclohexylamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dimethylaminopropylamine, hexamethylenediamine, m-toluylenediamine And the like.

The tackifier resin having an ester group is obtained by reacting with a compound having a carboxyl group such as acetic acid under a catalyst such as an acid.

These tackifying resins may be used alone or in combination of two or more. However, if the addition amount is too large, the peeling resistance performance is reduced. Therefore, it is preferable that the amount be within 30 parts by weight based on 100 parts by weight of the acrylic copolymer.

The tackifying resin having the above functional group may have a functional group such as a terpene resin, an aliphatic petroleum resin, an aromatic petroleum resin, an alicyclic petroleum resin, a coumarone resin, a styrene resin or a xylene resin. A tackifier resin having no tackifier may be used in combination.

The compound capable of reacting with a functional group is a compound having a functional group capable of reacting with the above-mentioned hydroxyl group, carboxyl group, vinyl group, epoxy group, isocyanate group, mercapto group, amino group, ester group and the like.

The compound capable of reacting with a hydroxyl group or an isocyanate group includes tolylene diisocyanate (TDI) and toluylene diisocyanate (TOD).
I), xylylene diisocyanate, aromatic diisocyanate compounds such as diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HMD)
I), aliphatic or alicyclic diisocyanate compounds such as isophorone diisocyanate (IDI), trimerene diisocyanate adduct of trimethylolpropane, triphenylmethane triisocyanate, and methylene bis (4-phenylmethane) triisocyanate. Examples include isocyanate compounds. Further, alkoxysilane compounds such as trimethoxysilane, triethoxysilane, and tributoxysilane can also be used.

The compound capable of reacting with the carboxyl group includes N, N'-hexamethylene-1,6bis (1-
Aziridine carboxamide), trimethylolpropane-tri-β-aziridinylpropionate, N, N ′
-Diphenylmethane-4,4-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β
And aziridine compounds such as-(2-methylaziridine) propionate.

Compounds capable of reacting with both a hydroxyl group and a carboxyl group include ethylene glycol diglycidyl ether, triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidylaniline, and diglycidylamine. , N, N, N ', N'-tetraglycidyl-m-xylylenediamine, 1,3-bis (N, N'
(Diglycidylaminomethyl) cyclohexane and the like.

Compounds that can react with vinyl groups include active sulfur, sulfur chloride, sulfur compounds such as dithiol compounds, various organic peroxides such as benzyl peroxide and lauroyl peroxide, trichloromelamine, hexachlorocyclopentadiene, Examples thereof include polyhalogen compounds such as chlorocyclopentadiene, trichloromethanesulfochloride and benzotrichloride, and azo compounds such as AIBN. Further, a photoinitiator such as benzoin or benzoin alkyl ether may be used as the compound.

As the compound capable of reacting with the epoxy group,
Examples thereof include acid anhydrides, compounds having a carboxyl group, and amino compounds. Examples of the compound capable of reacting with a mercapto group in the tackifier resin include a di- or polymethylolphenol resin, an isocyanate compound, and an epoxy compound.

Examples of the compound capable of reacting with the amino group in the tackifier resin include an isocyanate compound and an epoxy compound.

Examples of the compound capable of reacting with the isocyanate group in the tackifier resin include a compound having a hydroxyl group, an amino compound, a compound having a carboxyl group, and polymercaptan.

Compounds which can react with the ester group include
Examples include amino compounds such as triethylenetetramine and aminosilane coupling agents. The functional group and the crosslinking agent may be used alone or in combination of two or more.

The compound capable of reacting with the above functional group may be used as a cross-linking agent, and such a cross-linking agent is used when the functional group of the resin composition is a carboxyl group or a hydroxyl group.
The same cross-linking agent as used for the polymer cross-linking can be used. When the functional group is an epoxy group, examples thereof include an acid anhydride, a compound having a carboxyl group, and an amine compound.When the functional group is a mercapto group, a di or polymethylol phenol resin, an isocyanate compound, and an epoxy compound are included. Can be Further, when the functional group is an amino group, examples thereof include an isocyanate compound and an epoxy compound. When the functional group is an isocyanate group, examples thereof include a compound having a hydroxyl group, an amine compound, a compound having a carboxyl group, and polymercaptan.

As the acid anhydride, maleic anhydride,
Dodecenyl succinic anhydride, sebacic anhydride, phthalic anhydride, pyromellitic anhydride and the like, and as polymercaptan, 2,2-dimercaptoethyl ether,
1,2-dimercaptopropane, bis (2-mercaptoethylsulfide), trade name "Dion3-800L
C "(manufactured by Diamond Shamrock).

The compound having a hydroxyl group includes 1,1
4-butanediol, 2,3-butanediol, 1,
Examples thereof include 1,1-trimethylolpropane, polyoxypropylene glycol, polyoxyalkylene glycol, hydroxyquinone dihydroxyethyl ether, dihydroxybenzophenone, and hydroquinone.

It is preferable that the tackifying resin having a functional group has a softening point of 100 ° C. or higher, or a softening point of 100 ° C. or higher after completion of a crosslinking reaction between the resins by the functional group. If the temperature is lower than 100 ° C., not only does the interface flow at a high temperature and the high-temperature holding power is lowered, but also the creep flow of the surface is promoted and the peeling resistance is lowered.

Further, after applying a composition mainly composed of a tackifier resin having a vinyl group or an epoxy group as a functional group and a photopolymerization initiator as a crosslinking agent to the surface of the pressure-sensitive adhesive layer, The resin may be polymerized by irradiation. However, when the functional group is an epoxy group, the photopolymerization initiator uses a photocationic catalyst. When a hydrogen abstraction type photoinitiator such as benzophenone is used, a tackifier resin having no functional group can be polymerized.

As a photopolymerization initiator, a trade name of "Irgacure 261, 651, 184" is used as a photoradical catalyst.
(Manufactured by Ciba Geigy), trade name "Nisso Cure MA, E
MA, BMA, EHMA, IAMA, MKZ, MEK
Z, BP, MABP, CBP, MBO ”(manufactured by Shin Nisso Chemicals, Inc.), trade name“ Darocur 1116, 1173 ”(Me
rck) and the like, and as the photocationic catalyst, trade names “SP-150, 170, 171” (manufactured by Asahi Denka Co., Ltd.);
Product name “CI-1370, 2397, 2481, 262
4, 2639, 2064 "(manufactured by Nippon Soda Co., Ltd.), trade names" SI-60L, 80L, 100L, 110L, 180 "
L "(manufactured by Sanshin Chemical Co., Ltd.), trade name" PDI-105, MP
I-103, 105, BBI-101, 102, 10
3,105, TPS-102,103,105, MDS
−103, 105, 205, 305, BDS-105 ”
(Manufactured by Midori Kagaku Co., Ltd.), trade name "CDI-1012, CD
-1010 "(manufactured by Sartomer). These may be used alone or in combination of two or more. Examples of the hydrogen abstraction type photoinitiator include benzophenone, Michler's ketone, dibenzosuberone, and 2-ethylanthraquinone.

The amount of the compound capable of reacting with the above-mentioned functional group is such that the tackifying resin having the functional group and the compound capable of reacting with the functional group are mixed with the tackifying resin originally added. The added amount is preferably such that the total amount of the reactants and the reactants in the product is 10% by weight or more.

The amount of reactant W ₁ (% by weight) of the compound capable of reacting with the functional group was determined by gel permeation chromatography (GPC) to determine the peak area (S ₁ ) corresponding to the molecular weight of the tackifying resin of the compound before the reaction. From the decrease after the reaction (ΔS ₁ ), it can be determined by the following equation (1). W ₁ = ΔS ₁ / S ₁ × 100 (1)

However, the pressure-sensitive adhesive after the reaction is usually gelled by the cross-linking of the acrylic copolymer.
Cannot be measured. Therefore, the above measurement may be performed for an acrylic copolymer having the same composition and a small molecular weight that does not cause gelation, or the amount of the reactant may be measured by the method specified below for an adhesive that has caused gelation. May be required.

When a tackifier resin originally added, including a tackifier resin having a functional group, and a compound capable of reacting with the functional group and a cross-linking agent are used in combination, the formulation of the pressure-sensitive adhesive including the cross-linking agent is followed. , Injection of the same amount into GPC
C is measured, and the peak area (S ₂ ) corresponding to the tackifier resin molecular weight before the reaction is determined. Furthermore, the pressure-sensitive adhesive after the reaction was subjected to Soxhlet extraction for one week with a solvent such as ethyl acetate or toluene, and the obtained extract was dried and measured for the total weight, and extracted with respect to the weight of the tackifier resin originally added. The weight ratio of the tackifying resin thus obtained, that is, the extraction rate Ex (%) is determined.

Further, a tackifying resin having the same concentration as that of the above tackifying resin was subjected to GPC measurement, and a decrease in peak area (ΔS
₂ ) Ask for. The unextracted components were all reacted tackifier resins, and the amount of reactant W ₂ (% by weight) was determined by the following formula (2).
Can be obtained from W ₂ = (Ex × ΔS ₂ ) / S ₂ + (100−Ex) (2) (where, Ex (%) = weight of extracted tackifying resin /
Weight of tackifier resin originally added x 100)

Some of the crosslinking agents added to crosslink the acrylic copolymer also function as the compound. When such a compound is used, it is not necessary to particularly add the above-mentioned different compound. Absent.

The amount of the crosslinking agent is preferably such that the gel fraction after crosslinking is in the range of 15 to 50% by weight. If the gel fraction is less than 15% by weight, the creep characteristics are not improved, and if it exceeds 50% by weight, the peeling performance at low speed and the initial adhesive strength are undesirably reduced. The gel fraction is the weight ratio of the weight of the insoluble portion remaining after drying after immersing the pressure-sensitive adhesive composition after crosslinking in tetrahydrofuran to the pressure-sensitive adhesive composition before immersion after 24 hours.

When a crosslinking agent added to crosslink the acrylic copolymer is used as a compound capable of reacting with a functional group, crosslinking and tackification of the acrylic copolymer may be performed depending on the curing temperature for the reaction of the crosslinking agent. The rate of reaction of the resin changes. Usually, the lower the temperature, the higher the reaction rate of the tackifier resin. Therefore, in such a case, the curing temperature for the reaction of the crosslinking agent is preferably set to 40 ° C. or lower.
More preferably, it is lower than 20 ° C.

However, when the compound capable of reacting with the functional group is replaced with the above-mentioned crosslinking agent added to crosslink the acrylic copolymer, the gel fraction of the acrylic copolymer and the reaction ratio of the tackifying resin are independently controlled. In some cases, it may be difficult to satisfy the respective optimum ranges at the same time. Therefore, a compound different from the crosslinking agent may be added.

When a cross-linking agent for cross-linking the acrylic copolymer and a compound capable of reacting with the functional group of the tackifying resin are used in combination, the cross-linking of the acrylic copolymer is consumed based on the gel fraction of the acrylic copolymer. The amount of the cross-linking agent thus calculated is calculated, and the ratio is preferably such that the total amount of the reactant formed by reacting the compound with the functional group and the cross-linking agent is 10% by weight or more.

When the amount is less than 10% by weight, the improvement in peel resistance is insufficient. The maximum addition amount is when the amount of the reactant does not increase due to an increase in the addition amount of the compound. Addition of the compound beyond this does not improve the peeling resistance.

A tackifying resin or a crosslinking agent other than those described above may be added to the acrylic copolymer as long as the peeling resistance at low speed is not impaired. Examples of the tackifying resin include C5 (aliphatic) and C9 (aromatic) petroleum resins, α-pinene and β-pinene polymers, diterpene polymers and α-pinene-phenol copolymers. Or a derivative thereof, a xylene resin or a modified product thereof, an ester compound of rosin, and the like, and a compound of pentaerythritol ester of rosin is preferably used since it has good crosslinkability and a large effect of improving physical properties.

The type of the crosslinking agent is selected by copolymerizing a vinyl monomer containing a hydroxyl group or a vinyl monomer containing a carboxyl group in the acrylic copolymer as a crosslinking group point. Crosslinking agents that can react with both carboxyl groups can also be used.

The acrylic pressure-sensitive adhesive tape or tape according to the present invention according to claim 4, wherein the tackifier resin having a functional group on the surface of the pressure-sensitive adhesive layer containing the acrylic copolymer as a main component, and the functional group And a surface layer formed by reacting the crosslinking agent capable of reacting with a part of the tackifying resin.

The surface layer composition applied to the surface of the pressure-sensitive adhesive layer may further include, for example, a catalyst for accelerating crosslinking, an acrylic copolymer or the like for the purpose of adjusting surface energy or surface viscoelastic properties. A rubber component or the like may be added, and a filler or a softener may be added as necessary.

The coating thickness of the above composition is preferably 0.01 μm or more and less than 0.5 μm. More preferably, it is 0.03 μm or more and less than 0.3 μm. 0.01μ
If it is less than m, the peeling force at a low speed, which is the object of the present invention, will not be improved, and if it exceeds 0.5 μm, the initial adhesive force will decrease sharply and no adhesion will occur. The measurement of the coating thickness can be performed using an electron microscope (for example, a scanning electron microscope ABT-32 manufactured by Irie Seisakusho, JSM-5800LV manufactured by JEOL Ltd.).

As the base material used for the acrylic pressure-sensitive adhesive tape or sheet of the present invention, those used for ordinary pressure-sensitive adhesive tapes, for example, paper, nonwoven fabric, synthetic resin films such as polyester and polyolefin, polyolefin, polyurethane And foamed sheets of synthetic resin such as polychloroprene and acrylic resin, and those obtained by molding an acrylic pressure-sensitive adhesive itself into a sheet.

The method for producing the acrylic pressure-sensitive adhesive tape or sheet of the present invention is not particularly limited. For example, by a coating machine such as a roll coater which is usually used, the pressure-sensitive adhesive composition is directly applied to one surface of the substrate, or the pressure-sensitive adhesive composition is applied to a release sheet to form a pressure-sensitive adhesive layer, The adhesive layer is provided by bonding this to a substrate. Next, on the surface of the pressure-sensitive adhesive layer, a resin composition containing a tackifier resin having a functional group and a crosslinking agent capable of reacting with the functional group as a main component is directly applied by a gravure coater or a sprayer, or separated separately. A method in which a composition layer formed by applying to a sheet surface is bonded to the surface of the pressure-sensitive adhesive layer to form a surface layer, and the like can be mentioned.

In the above-mentioned production method, a composition obtained by dissolving the pressure-sensitive adhesive composition and the composition to be coated on the surface of the pressure-sensitive adhesive layer in an organic solvent or the like may be used. Examples of the organic solvent include ethyl acetate, toluene, acetone, tetrahydrofuran, ethyl alcohol, methyl alcohol and the like.

The above composition may be subjected to light irradiation or heat curing after the production of the acrylic pressure-sensitive adhesive tape or sheet in order to crosslink the resins after application to the pressure-sensitive adhesive layer surface.

[0061]

Embodiments of the present invention will be described below. Preparation of acrylic copolymer 96.9 parts by weight of n-butyl acrylate, acrylic acid 3
Parts by weight, 0.1 parts by weight of 2-hydroxyethyl acrylate, and 0.06 parts by weight of lauryl mercaptan as a chain transfer agent together with 80 parts by weight of ethyl acetate, a stirrer, a reflux condenser, a thermometer, a dropping funnel and nitrogen. The mixture was charged into a five-necked flask equipped with a gas inlet, stirred and dissolved to form a homogeneous mixture, and purged with nitrogen gas for about 30 minutes to remove oxygen present in the monomer solution.

Thereafter, the air in the flask was replaced with nitrogen gas, the temperature was increased while stirring and maintained at 70 ° C., and a solution in which 0.03 part by weight of benzoyl peroxide was dissolved in 1 part by weight of ethyl acetate was added dropwise. After dripping with a funnel, polymerization reaction was carried out at the same temperature for 10 hours to obtain an acrylic copolymer solution. When the molecular weight of this copolymer was measured by GPC, the weight average molecular weight (Mw) was 510,000 and the molecular weight distribution (Mw / Mn) was 3.3.

Example 1 A crosslinker (ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane, ethyl acetate solution, solid content 55% by weight, trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added to 100 parts by weight of the above acrylic copolymer solution. 0.9 part by weight of “Coronate L55E”) was added thereto, and the mixture was uniformly mixed while being diluted with toluene to obtain an acrylic pressure-sensitive adhesive composition having a solid content of 45% by weight.

Thickness 38 μm with corona discharge treatment on the surface
m of polyethylene terephthalate substrate,
The resultant was dried in a gear oven at 5 ° C. for 5 minutes to obtain a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 50 μm, and cured at 40 ° C. for 3 days. The gel fraction of this pressure-sensitive adhesive was 40% by weight.

Ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane as a crosslinking agent was added to 100 parts by weight of a pentaerythritol esterified product of disproportionated rosin having a softening point of 100 ° C. and a hydroxyl value of 55 mg KOH / g as a tackifying resin. 6% by weight of 55% by weight, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate L55E"), and a solution having a solid content of 5% by weight by adding ethyl acetate was applied to the surface of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape. It was applied with a gravure coater, dried at 110 ° C. for 9 minutes with a hot air drier, and then cured at 40 ° C. for 3 days.

Example 2 Softening point 1 as tackifying resin
Pentaerythritol esterified polymer rosin having a hydroxyl value of 31 mgKOH / g at 25 ° C. (Arakawa Chemical Co., Ltd.
An adhesive tape was obtained in the same manner as in Example 1 except that the compounding amount of the crosslinking agent was changed to 3 parts by weight using a trade name of “Pencel D125”.

(Example 3) Softening point 1 as tackifying resin
Using a pentaerythritol esterified product of disproportionated rosin having a hydroxyl value of 18 mgKOH / g at 25 ° C. (trade name “Super Ester A125” manufactured by Arakawa Chemical Co., Ltd.)
An adhesive tape was obtained in the same manner as in Example 1 except that the amount of the crosslinking agent was changed to 3 parts by weight.

Comparative Example 1 An adhesive tape was obtained in the same manner as in Example 1 except that nothing was applied to the surface of the adhesive layer.

Comparative Example 2 A pressure-sensitive adhesive tape was obtained in the same manner as in Example 1, except that no crosslinking agent was added to the composition applied to the surface of the pressure-sensitive adhesive layer.

Comparative Example 3 100 parts by weight of the acrylic copolymer used in Example 1 was added with a softening point of 1 as a tackifying resin.
Pentaerythritol esterified polymer rosin having a hydroxyl value of 31 mgKOH / g at 25 ° C. (Arakawa Chemical Co., Ltd.
20 parts by weight of trade name “Pencel 125”) were added, and the mixture was diluted with toluene and uniformly mixed to obtain an acrylic pressure-sensitive adhesive composition having a solid content of 45% by weight, and to this was added trimethylolpropane tolylene diisocyanate as a crosslinking agent. The product was added with 3 parts by weight of an ethyl acetate solution (solid content: 55% by weight, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L55E), and mixed uniformly to obtain an acrylic pressure-sensitive adhesive solution.
A conventional acrylic pressure-sensitive adhesive solution was applied to a 38 μm-thick polyethylene terephthalate substrate having a surface subjected to a corona discharge treatment, and dried in a gear oven at 110 ° C. for 5 minutes to obtain a pressure-sensitive adhesive tape having a 50 μm-thick pressure-sensitive adhesive layer. , 40 ° C
For three days. The gel fraction of this adhesive is 30% by weight
Met.

Example 4 To 100 parts by weight of the above acrylic copolymer solution, 28 parts by weight of an ethyl acetate solution (hydroxyl value 55, solid content 55% by weight) of a rosin ester tackifying resin were added and mixed well. Ethyl acetate solution of tolylene diisocyanate adduct of trimethylolpropane as a crosslinking agent (solid content: 55% by weight, manufactured by Nippon Polyurethane Industry Co., Ltd.)
5 parts by weight of trade name "Coronate L55E") were blended to obtain a crosslinkable acrylic pressure-sensitive adhesive composition. Using this pressure-sensitive adhesive, a pressure-sensitive adhesive tape was prepared in the same manner as in Example 1;
Cured at 65% RH for 3 days.

Example 5 Curing conditions were 18 ° C. and RH 65
% Was changed to 7 days to prepare an adhesive tape in the same manner as in Example 4.

(Example 6) Curing conditions were 5 ° C and RH 65%.
The pressure-sensitive adhesive tape was produced in the same manner as in Example 4 except that the pressure was changed to 14 days.

(Example 7) Curing was carried out under the same conditions as in Example 5 except that the ethyl acetate solution of the rosin ester tackifying resin had a hydroxyl value of 20 and the addition amount of the crosslinking agent was 2.5 parts by weight. Thus, an adhesive tape was produced.

(Example 8) Curing was carried out under the same conditions as in Example 6 except that the ethyl acetate solution of the rosin ester tackifying resin had a hydroxyl value of 20, and the addition amount of the crosslinking agent was 2.5 parts by weight. Thus, an adhesive tape was produced.

(Comparative Example 4) Curing conditions were 30 ° C and RH65.
%, And a pressure-sensitive adhesive tape was produced in the same manner as in Example 7 except that the time was changed to 14 days.

Comparative Example 5 An adhesive tape was prepared by curing under the same conditions as in Comparative Example 4 except that the amount of the crosslinking agent was changed to 1.2 parts by weight.

Comparative Example 6 An adhesive tape was produced in the same manner as in Example 1 except that the amount of the crosslinking agent was 1 part by weight and the curing conditions were 23 ° C. and RH 65% for 14 days.

Comparative Example 7 An adhesive tape was prepared by curing under the same conditions as in Comparative Example 4 except that the amount of the crosslinking agent was changed to 5 parts by weight.

(Comparative Example 8) Curing conditions were 40 ° C and RH65.
%, And a pressure-sensitive adhesive tape was produced in the same manner as in Comparative Example 7 except that the time was changed to 14 days.

Performance Evaluation of Pressure-Sensitive Adhesive Tape (1) Confirmation of Crosslinking of Surface Coating Composition Each of the surface coating composition immediately after compounding and the crosslinked one was dissolved in tetrahydrofuran so as to have a solid concentration of 0.2% by weight. , GPC was used to measure the weight average molecular weight and peak area, and the presence or absence of the high molecular weight component after crosslinking and the reduction ratio of the peak area were determined.

(2) Adhesive force to polypropylene adherend An adhesive tape having a width of 20 mm was adhered to a polypropylene plate with a load made by reciprocating a 2 kg rubber roller once.
At 20 ° C for 20 minutes, then at 23 ° C, 40 ° C, 60 ° C and 8 ° C.
After a lapse of 30 minutes at 0 ° C, the peeling force is measured by a peeling test in a 90 ° direction to determine the adhesive strength. The peeling speed at this time was measured at six points in the range of 0.01 to 5 mm / sec, and based on the speed dependency of the peeling force at each of the obtained temperatures, the temperature was set to 60 ° C. as a reference according to the temperature-speed conversion rule. A master curve having a peeling speed of 10 mm / sec and 0.0
A peel force of 01 mm / sec was read.

(3) Holding force against SUS According to JIS Z0237, width 20 mm, length 100
1.5mm thick, 25mm wide adhesive tape
SUS304 plate having a length of 100 mm and a length of 100 mm.
Leave in an atmosphere of 0% RH for 20 minutes, then in an atmosphere of 80 ° C. for 20 minutes, apply a load of 1 kg to the lower end of the adhesive tape, maintain the adhesive tape vertically, and drop it within 1 hour (min) or 1 minute. The displacement distance (mm) after time was measured. The above results are shown in Tables 1 and 2.

[0084]

[Table 1]

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[Table 2] TF A; pentaerythritol esterified product of disproportionated rosin having a hydroxyl value of 55 mg KOH / g TF B; superester A-115 having a hydroxyl value of 20 mg KOH / g (Arakawa Chemical Co.) TF C; disproportionation of a hydroxyl value of 7 mg KOH / g Pentaerythritol ester of rosin

[0086]

As described above, the acrylic pressure-sensitive adhesive of the present invention has the above-mentioned constitution, so that it is easier to control the surface free energy than the conventional mixed system of an acrylic copolymer and a tackifying resin. Therefore, according to the acrylic pressure-sensitive adhesive tape or sheet of the present invention using this, it becomes easy to approach the surface free energy of the low-polarity adherend, and the adhesiveness is improved more than before. In addition, plasticization of only the surface or interface can be effectively suppressed without changing the properties of the bulk. as a result,
From the improvement of adhesion by controlling surface free energy and the improvement of interfacial adhesion holding force (reduction of flow separation) by suppressing creep flow at the surface or interface, the separation resistance to low-polarity adherends is greatly improved. In particular, it exerts an effective holding force against a peeling force of a constant load. In addition, since bulk design can be performed regardless of surface properties, the range of adhesive designs for other adhesive properties is expanded, and adhesive tapes or sheets with balanced adhesive properties are obtained. It can be suitably used as an adhesive tape or a double-sided adhesive tape.

Claims (5)

[Claims] 1. A pressure-sensitive adhesive containing an acrylic copolymer as a main component, wherein the pressure-sensitive adhesive comprises a tackifier resin having a functional group, a compound capable of reacting with the functional group, and the tackifier resin. An acrylic pressure-sensitive adhesive characterized by containing a reactant reacted with a part of the acrylic pressure-sensitive adhesive. 2. The acrylic pressure-sensitive adhesive according to claim 1, wherein the compound capable of reacting with the functional group is a crosslinking agent. 3. The acrylic pressure-sensitive adhesive according to claim 1, wherein the tackifier resin having a functional group is an esterified rosin compound. 4. A pressure-sensitive adhesive tape or sheet in which a pressure-sensitive adhesive layer containing an acrylic copolymer as a main component is provided on one surface of a base material, wherein the pressure-sensitive adhesive resin having a functional group is provided on the surface of the pressure-sensitive adhesive layer. An acrylic pressure-sensitive adhesive tape or sheet comprising a surface layer formed by reacting a crosslinking agent capable of reacting with the functional group with a part of the tackifier resin. 5. The acrylic pressure-sensitive adhesive tape or sheet according to claim 4, wherein the tackifier resin having a functional group is an ester of a rosin compound.